Field emission devices are packaged vacuum microelectronic devices that are used in connection with computers, television sets, camcorder viewfinders, and other electronic devices. Field emission devices generally have a rear plate and a front plate facing each other with a narrow vacuum gap therebetween. In large field emission devices, a number of spacers are positioned between the rear plate and the front plate to prevent atmospheric pressure from collapsing the plates together. The rear plate typically has a base substrate upon which a number of sharp, cone-shaped emitters are formed, an insulator layer positioned on the substrate having apertures through which the emitters extend, and an extraction grid formed on the insulator layer around the apertures.
One problem with field emission devices is that the internal components continuously outgas, which causes the performance of field emission devices to degrade over time. The effects of outgassing are minimized by placing a special material to absorb the gas (commonly called getter material) within the sealed vacuum chamber. Accordingly, in order to absorb the gas in the vacuum chamber over a field emission device's lifetime, a sufficient amount of getter material must be incorporated into the field emission device before it is sealed.
In operation, getter materials are usually arranged in a corner of the field emission device, but the conductance from the outgassing site to these getters are limited by the narrow space between the flat plates, causing reduction of the getters' absorption efficiency and in consequence the display's performance and lifetime. There are also according solutions in which a separate space for containing getter materials is added to the device, but the structure thereof becomes complicated and the manufacture cost will be increased.
What is needed, therefore is to provide a field emission device having getter material that has a high absorption efficiency.